By following these steps:
1. Click the 3 dots next to your Folder/Report and clicking Share.
2. If you want to provide baseline access level to all users within your Organisation:
a) Select the Organisation Access dropdown
b) Choose either Viewer or Editor
3. If you want to set access just for specific users:
a) Search for the user's email in the User Access dropdown
b) Select either Viewer or Editor
c) Click Add or Save
NOTES:
If you set User Access for a Folder, any Reports within that Folder will inherit that Access permission.
User Access overrides Organisation Access - this means that if you set Organisation Access on a Folder after adding Reports to that Folder, you will still need to set Access on the Reports.
If you have created either a Report that exists outside of a Folder or inside of a Folder without any User Access, you must set Access on that Report for anyone else to see it.